BORROWINGS (Details 4) (USD $)	12 Months Ended			0 Months Ended	12 Months Ended			1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jan. 15, 2010 7 500% convertible senior notes	Dec. 31, 2012 7 500% convertible senior notes	Dec. 31, 2011 7 500% convertible senior notes	Dec. 31, 2010 7 500% convertible senior notes	Jul. 31, 2012 7.0% convertible senior notes	Mar. 31, 2012 7.0% convertible senior notes	Dec. 31, 2011 7.0% convertible senior notes
Details of Company's borrowings
Interest rate (as a percent)					7.50%					7.00%
Convertible senior notes issued, principal amount				$ 172,500,000
Conversion price per share (in dollars per share)					$ 7.05
Total net proceeds from senior notes	111,418,000	250,669,000
Carrying amount of equity component included in paid-in-capital					10,000,000	10,000,000
Convertible debt principal amount					172,500,000
Debt discount, unamortized					6,500,000	7,800,000
Debt discount, amortized					1,300,000	1,200,000	1,000,000
Effective interest rate to amortize debt discount (as a percent)					8.60%
Interest expense, recognized					12,900,000	12,900,000	12,400,000
Principal amount of debt extinguishment								112,000,000	23,100,000	45,500,000
Loss on repurchase of convertible notes									400,000	1,700,000
Write-off of unamortized debt issuance costs	4,224,000	2,194,000	8,160,000						200,000	100,000
Total borrowings	$ 6,338,407,000	$ 6,778,208,000			$ 166,000,000	$ 164,700,000